If I throw a Flamestrike at you and score 3 net hits, that's 2P Fire you have to resist every round until you put it out. If I throw a Fireball, the defenders take an area dodge penalty if I read this correctly, meaning I might score more net hits. If I were to manage 5 net hits, which I can easily do if I force a few rerolled dice, then they'd have to resist 3P Fire every round.